Rubber composition



l Patented Apr-J 15, 1924.

' Ho Drawing.

UNITED STATES;

' mum ems runs, or new You, n. Y.

Rosana comrosrrrou.

To all wlwm-z't'niay concern:

Be it known that I, KARL B. LAMB, a citiv zen of the United States, residing at New York city, in the county ofNew York, State of New York, haveinvented certain new and useful Improvements in Rubber Compositions; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable. others skil-lcdin the'art to which itupp'ertams tomake and use the se ne. The present invention relates to rubber compositions of a composite character, and

particularly to compositions of theMcharac ter in which black'pigments aroused.

' In the manufacture of rubber compositions it is customary to compound with the rubber: various compounding ingredients, such as pigments, fillers, and inorgamcmaterials of various kinds to give to the rubber the desired"physical and other properties. For making black or grey rubber compositions, lamp black and gasblack are frequently used." These black pigments, however, are lacking in bodyt and, where inorganic compounding ingredients are desired {for adding body to the compositions and to reduce the pure rubber content, other pig-- ments'or fillers than. the carbon lamp black are added 1 I According to the present. invention, the rubber compositions are made with the incorporation therewith of a composite black pigment of an intense black color which nevertheless combines in its' properties those of black or a body-giving filler or compounding material with those of a color-giving pigment. The-invention is characterized. by the compounding with the rubber and other ingredients of such a composite pigment, that is, one which combines in aslngle composite Y material, both a filler or body-giving material and ablackpigment, so intimately associated with each other that a relatively large amount of the filler or body-giving material, is present without destroying the idesired'black properties of the composition.

' The composite pigments or compounding material utilized in the new compositions are made from spent fullers earth which is a by-product' commonly considered to have s earth little if any value and frequentl thrown ll r " away as worthless. The spent in isfthat which resultsfromthe refining and decolorizing ofoils and fats. (for examspgai vegetable o ls and se ues as cotton Application flied Iehruary 2, 1022, Serial No. ssa'asa.

oil) withv fullers earth, which loses its effectiveness after a'certain-p'eriod of use and Q fspent. .After the removing-cf as, much as possible'of the oil therefrom, the spent fullers earth still contains a considerable amount of oil admixed therewith. Upon subjecting the spent fullcrs earth toa rega lated car onizin operation the oil in the spent earth is car ionized and converted into a black igment in most intimatcdistribution witi respect to the fullers earth base so that the product of the regulated carboni zation operation is a composite product'with the carbon from the oil combined in an integral or intimatemanner with the fullers earth base.

The production of the composite pigment may be carried out in various ways of which the following illustrations are specific examples:

The s nt intimate y distributed throughout its mass. may be placed in an, open pan and heated by direct flame until the gases resulting be stirred continually or from time to time throughout the operation. As the carbonh zation progreses, the earth. becomesblack in color until the product as a whole is an intense black. n 'The further heating of the mass should bet-hen stopped, so that the product may cool.

While carbonization may be satisfactorily accomplished in the manner described, a

preferred method for the commercial production of the pigment is tocarbonize 1t in a closed retort or rotary furnace, preventing oxidation as much as possible by the proper control of the air in the retortor furmice. The heating should be regulated so that the mass of earth and oilburns quietly. A rotary furnace provides an automatic'stirring of the material and also allows a'better recovery in the furnace itself; of lamp black formed from the burning-of theoil. After the carbonization has pro point that all the oil has been carbonized,

heating should be stoppedin order to revent oxidation, and the resulting pro not. J allowed to cool. When the carbonized ma-' nited. The heating of the earth should be fullers earth, having the oil v seed to such a I terialadpreparedi either of the ways describ' p y then ground in aball mill until a. siiflicient degree offineness for pigment purposes isobtained. I

, During thecarbonizing operation a 'considerable amount of smoke is formed from the decomposition of the oil content'of' the 'spentfullers earth, particularly if the burning, carbonizin'g, and stirring operations are carried ,onat a low temperature, and with limited access of air. The finely divided carbonof this smoke appears to be precipitated in part throughout the fullers earth, al-

though a considerable amount of it escapes as smoke with the gaseous products of the earboniz'ing operation. This smoke can be treated .for the precipitationand recovery I of thecarbon or lamp black therefrom, in

black thus separatel .valuable product an can be separately used in place of .lam f black made, from other sources; It can a so be advantageously com:-

much. the same way that lamp black is recovered when made from oil.

recovered is itself a bined I with the composite blackv pigment formed "by carbonizing the Spent ,fullers earthitself, thereby increasing the intensity of the black color of the composite pigment 30. rately collected lamp black thereto.-

of. the fullers earth; (2) the recipitation of adding acertain percentage of the sepa- The decomposition and carbonization of the oil'throu bout the mass of the fullers earth results ,m a most intimate production and de sition of the carbon black in and upon t e'particlesof. the earth,- so that the product has an intenseblack color. The

lack color thus imparted to the earth may be considered to-be due to three causes, name- 1y, (1) to the actual formation of finely divided carbon .from the oil. within the body the oil-smoke in a finely divi ed state within the massof the .fullers earth; and (3) the incorporation of the lamp black separately precipitated from thesmoke, when this separate yproduced lamp black is admixed with the; original composite pigment. Asa result'ofthis intimate production and deposition of the carbon blackin and upon the particles of the'earthyeven though but a i small percentage of the tot-alweigl'it of the composite pigment-is made of. the carbon black, the whole product is nevertheless of aniiitense black color. The fullers earth, which is itself of a porous structure,i1ppears to be intimately coated or plated with the deposited black. As a result,'the composite product, although of an intense black color, nevertheless has a relatively large amount is cool," it can be disehargedand The lamp of fullers earth-intimately combined therewith, so that the com osite pigment 'can be. usedjto particular a vantage for purposes Where a pigment having considerable body,- as well as an intense black color, is desired. The composite pigment obtainable in themanner above described forms a valuable compounding material for making rubber compositions and imparts to the COIliPOSl? tion's characteristic properties. Although the composite pigment has a considerable body, it neverthe ess is of an intense black color,

ounding ingredients are desired and where, in addition, a black or grey color is also desired in therubber composition.

The compounding of; the composite pig,- ment with the rubber and otheringredients (such as vulcanizing agent, etc.) can be effooted in the usual way, for example, by add- 111% the composite pigment while the rubber is eing masticated on the rubber mill. The resulting composition can then be subjected and it can be used where body-givingconr to vulcanization in much the, usual way.

For making the compositions of products of different charactersv and for difi'erent pur- I poses, other and varying compounding in: gredients can also be used. So also,"- the compositions may be soft rubber coin ositions, vulcanized with. a small ainount o sill fur, I or they may be. hard rubber compositions, made with alarger amount of sulfur.

, The-present application is in part a con-" tiniiation of my prior application 'Ser. No.

464,986, filed April 27, 1921, in which the; composite pigment itself is claimed, together 3. A rubber composition comprising, rubher and a composite black pigment, said pigment being made up of a body-giving pigment base and a carbonized black pigment coating and integrally combined with the base. In testimony whereof-I aflix my signature.

KARL BARRE LAMB. 

